This invention relates to the treatment of piece goods in a jet dyeing or finishing machine and more particularly, to the detection of abnormal movement of piece goods in a jet dyeing or finishing machine.
Such jet dyeing or finishing machines generally utilize a vessel containing a treating bath of processing liquid, through which a piece of textile material is circulated in endless rope form. The vessel typically contains a treatment chamber containing a bath of treatment liquid through which the textile rope passes in a compact plaited plug form. However, some modern jet dyeing and finishing machines apply the treatment liquid primarily using the jet nozzle, resulting in little or no submerging of the rope plug in any liquid in the treatment chamber. A rope circulating system progressively withdraws the rope from the leading end of the plug and returns it to the trailing end of the plug under the influence of the processing liquid being applied and circulated by a jet assembly through which the rope passes during circulation.
Such machines have presented problems in the wet processing of surface sensitive textile fabrics such as fabrics formed of relatively low twist spun yarns, fabrics formed of loosely knit, stretchable construction, certain plush or pile and other delicate fabrics. Fabrics of these types are especially susceptible to various forms of surface damage and it is not unusual for such machines to produce fabric wrinkling, fuzziness, excessive stretching, and, in pile fabrics, disoriented pile.
In order to alleviate this problem, a number of machines have used a low traction surface for the outer drum of the lifter reel. Typically, such a lifter reel would have no frictional material on its outer surface but may have some dimple-type extrusions thereon. Such a surface cannot provide enough traction to pull the material over the lifter reel against any significant resistance, such as a tangle in the rope coming from the plug. Accordingly, the material may slip against the reel as the reel continues to be driven at a predetermined rate even if the rope slows, or in some instances, stops.
Such treatment vessels are known to induce turbulence into the liquor bath in order to facilitate movement of the rope and improve its contact with the treating liquor baths. Improved plug contact with the treating liquor is also facilitated by having a generally irregularly shaped transfer section in the interior of the tubular tub. However, these characteristics tend to interfere with the path of the fabric rope during treatment and thus restrict the rope's movement. This problem is compounded by the fact that the fabric rope is by nature prone to entanglement as it is plaited into plug form, and as the plug moves through the treatment chamber such entanglement may in some instances result in a resistance opposing the force of the lifter reel and jet sufficient to slow or even stop circulation of the rope. The tangling presents significant problems since slowing or stopping of the material in the treating bath can result in unacceptable treatment results or may damage delicate fabrics at the point of entanglement and both slowing and stopping require operator attention.
Many existing machines detect abnormal rope movement, which could be caused by a tangled fabric rope, using a so-called "trip motor" connected to the lifter reel to detect a certain amperage when the rope of material becomes tangled, inhibiting rotation of the lifter reel and thus increasing the load on the drive motor. A "trip motor" will automatically disengage or shut down upon drawing a predetermined amount of current or "load." However, when treating delicate, smooth fabrics utilizing the aforementioned low traction lifter reel surfaces, even if the fabric rope becomes tangled, the continuously driven lifter reel will still rotate under application of drive power, sliding on the slowed or stopped rope and will not load the motor enough to draw the necessary amperage to trip the motor and signal an alarm condition. Therefore, it would be advantageous if drive of the lifter reel could be interrupted to determine the rope circulation rate. By stopping the lifter reel, a true picture of rope movement could be assimilated, absent the influence of the lifter reel driving movement.
An attempt to detect rope entanglement utilizing a different apparatus is discussed in U.S. Pat. No. 3,830,084 to Caputi which controls the operation of a dyeing or finishing machine using a control apparatus which comprises a pulse generator in the form of a permanent magnet attached to the rope being dyed and a pulse detector device having a number of ferromagnetic cores mounted on an annular collar that is electrically connected to a signaling device. Rope movement causes the permanent magnet to cyclically pass through the annular collar, thereby inducing an electromotive force in the coils formed by the ferromagnetic cores which is transmitted to the signaling device. A pulse is detected each time the rope completes a circuit of its closed loop dyeing path. If the rope stops moving, the expected pulse is not detected, and, in response, an alarm is sounded to signal an operator that rope travel has been reduced below tolerance levels or has ceased altogether. The Caputi apparatus and method, however, requires significant modifications and/or additions to the jet dyeing machine to be monitored and requires the application of a magnet to the rope.
Thus, a simple, inexpensive, and reliable solution to the problem of detecting rope entanglement in jet dyeing machines is needed.